Judge Randall Rader of the U.S. Court of Appeals for the Federal Circuit has announced his resignation as chief judge of the court following a controversy over an email he sent to a BigLaw partner.

The court announced on Friday that Rader will step down as chief judge at the end of May, though he will continue as an active judge on the court, report Legal Times and the Wall Street Journal (sub. req.).

According to a Wall Street Journal (sub. req.) article published on Thursday, Rader had raised eyebrows after he sent a patent lawyer an email earlier this year that praised the lawyer’s appellate skills and encouraged him to share the endorsement with others. The newspaper relied on unnamed sources for the report.

The lawyer who received the email was Edward Reines of Weil Gotshal & Manges, the sources told the Wall Street Journal. Reines had previously appeared before the Federal Circuit in cases involving Microsoft and Medtronic, and Rader had originally participated in those cases.

Rader later recused himself from those two cases, the Federal Circuit revealed earlier this month. As a result, the court reissued an opinion in one of the cases and a judicial order in the other.

According to the Wall Street Journal, “The incident shines a light on the clubby world of patent law where judges from the Federal Circuit and its top lawyers often develop a familiarity that can spill over into friendship. Judges from that court and lawyers often appear together on panel discussions in Washington and Silicon Valley, and hobnob at patent-law conferences.”

A court spokeswoman told the Wall Street Journal that Rader had declined to comment. Legal Times was unable to reach Rader for comment.